Multilateral technologies allow an operator to drill a parent wellbore and subsequently drill a lateral wellbore extending from the parent wellbore at a desired orientation and to a chosen depth.
To drill a multilateral well, the parent wellbore is first drilled and then at least partially lined with a string of casing or another type of wellbore liner. The casing is cemented into the wellbore to strengthen the parent wellbore and facilitate the isolation of certain areas of the formation behind the casing for the extraction and production of hydrocarbons. To drill a lateral wellbore from the parent wellbore, a casing exit (alternately referred to as a “window”) is created in the casing of the parent wellbore. The casing exit can be formed, for example, by positioning a whipstock at a predetermined location in the parent wellbore to deflect one or more mills off the whipstock and into engagement with the casing to mill through the casing. A drill bit can be subsequently deflected through the casing exit to drill the lateral wellbore, which can then be completed as desired.
Once the lateral wellbore is drilled and completed, stimulation operations may be undertaken in the lateral wellbore by installing a lateral junction isolation tool at the junction between the parent and lateral wellbores. To install the lateral junction isolation tool, a workover whipstock is commonly first installed at the junction to deflect the lateral junction isolation tool partially into the lateral wellbore so that it can be set and provide a transition between the parent and lateral wellbores. Upon completing the stimulation operation in the lateral wellbore, the lateral junction isolation tool is pulled out of the well and a subsequent trip downhole is made to retrieve the workover whipstock, and thereby providing full access to the parent wellbore. A mainbore junction isolation tool is then installed at the junction between the parent and lateral wellbores to undertake stimulation operations in lower portions of the parent wellbore.
This process of stimulating both the parent and lateral wellbores in a multilateral wellbore can be trip intensive; i.e., meaning that it can require several downhole trips into the well. Reducing the number of trips into the well while being able to perform the same functions can save a significant amount of time and expense in multilateral operations.